Particle filters are installed in the exhaust gas line of diesel engines to collect any particulate matter conveyed in the exhaust gas flow, particularly soot particulates. Such particle filters must be cleaned periodically to prevent accumulated soot on the particulate filter excessively increasing the exhaust gas backpressure, which impairs the efficiency of the diesel engine. Soot oxidation, also called soot combustion is use free the particle filter surface facing the incoming flow from the accumulated soot particles. The soot combustion can either be triggered, or it can occur spontaneously if suitable conditions exist. The latter occurs if the exhaust gas temperature flowing into the particle filter is higher than the soot ignition temperature, and if a sufficient quantity of oxygen is exists in the exhaust gas flow.
To ensure that a sufficient soot quantity has accumulated on the particle filter surface facing the incoming flow, regenerating the particle filter by triggering a soot oxidation should only occur when the particle filter has a certain soot charge state. This ensures that the desired oxidation proceeds as required. If the soot oxidation process is triggered when there is insufficient soot accumulation on the particle filter, the soot oxidation could be incomplete, causing the problems noted above. For this reason, before the regeneration of the filter is initiated, a determination of the soot charge state of the particle filter is normally done in connection with active regeneration processes. The pressure is typically measured in the exhaust gas flow upstream and downstream of the particle filter in order to detect the soot charge state of the particle filter. By observing the pressure differential and the air and fuel quantity fed into the internal combustion engine, the actual soot charge state of the particle filter can be determined depending on the respective characteristic curves of the internal combustion engine. The characteristic data of the engine are required to be able to determine the charge state of a particle filter installed in an exhaust gas line of an internal combustion engine, in particular a diesel engine, in this manner. For this reason, this method is difficult to use for retrofit purposes or for small run series, because each system must be adapted to the respective characteristic data of the engine. This method is also considered disadvantageous because the air quantity fed into the internal combustion engine for the combustion process must be measured, and because there is not always sufficient space available to install such volumetric air flow metering unit.
The foregoing example of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.
Based on this discussed prior art, the purpose of the invention is to develop or further develop the method mentioned at the outset and the device mentioned at the outset in such a way that the soot charge state of a particle filter installed in the exhaust gas line of an internal combustion engine and the air volume fed into the internal combustion engine can also be detected irrespective of whether the engine characteristic data are available.